This invention is directed toward method and apparatus for loading blow molding machines with temperature-conditioned workpieces such as elongated thermoplastic parts which are to be subsequently further shaped into molecularly oriented hollow articles such as containers.
In U.S. Pat. No. 3,754,851, a system is disclosed for blowing articles from molded preforms which are brought to orientation temperature in an intermediate conditioning step. In this approach heat is removed from the preform during conditioning and such has become known in the art as a "cool-down" process. It is likewise known to add heat to preforms to bring them up to orientation temperature prior to finish forming as is typically disclosed in U.S. Pat. No. 3,715,109 and other related prior art, and such has become known in the art as a "reheat" process. In high speed, high capacity forming lines utilizing either of these approaches, it is clearly desirable to optimize the temperature-conditioning part of such techniques in order to keep fabricating costs related to this step at an absolute minimum. Thus, it is desirable to process a large number of parts at the same time, to minimize handling and reorienting movement of the distortable parts during conditioning, and during transfer to the blowing equipment and to expose each part as uniformly and completely as possible to the heat sink to minimize exposure time and complexity of apparatus.
Though the above-mentioned prior art has generally been successful in implementing cool-down and reheat processing, it is deficient in one or more aspects of the temperature-conditioning and blow molding equipment loading phases, especially when considered in the environment of a high speed, continuous, large capacity forming line.